As the coronavirus pandemic spreads worldwide, doctors, scientists and heads of government have said that once collective immunity is achieved, the spread of the virus will be less threatening. Collective immunity is reached when the majority of a given population – 70 to 90% – becomes immune to an infectious disease, either because they become infected and have recovered, or through vaccination. When this happens, the disease is less likely to spread to people who are not immune, because there simply are not enough infectious carriers to reach them.
There are only two ways to get there: generalized vaccination, which for Covid-19 is still several months away, or generalized infections which lead to immunity.
Most doctors and experts agree that allowing Covid-19 to plow people could help achieve collective immunity faster, but it would also overwhelm hospitals. More and more people are dying, not only from coronavirus, but from other infections. That’s why we’re all stuck at home – we flatten the curve.
“The advantage of expanding the number of cases is that we will not exceed the capacity of hospitals to care for particularly sick people,” Dr. H. Cody Meissner, chief of pediatric infectious diseases at Tufts University Medical, told CNN. School. Michael Smerconish in March.
Then there is the problem that we don’t really know how immunity works with this virus.
World Health Organization (WHO) infectious disease epidemiologist Dr. Maria Van Kerkhove said that it is unknown whether people who have been exposed to the virus are fully immune to it and, if so, , for how long. That’s why governments should wait for a vaccine, she said.
The WHO has “seen preliminary results, preliminary studies, pre-published results, in which some people will develop an immune response,” said Van Kerkhove. “We don’t know if that actually confers immunity, which means they are fully protected. “
A vaccine is a better answer, she added. “I mean, recently we had over 130 developers, scientists, companies come together to say they would be willing to work with us – to work globally to advance a vaccine. And this is something that we are going to push and the whole world is waiting for. ”
And while young people are much less likely to die from Covid-19, they can still fall ill enough to require hospitalization.
Although catching Covid-19 once makes people immune to future infection, the United States has not had enough cases to come close to generalized immunity.
“The level of people who have been infected, I don’t expect it to reach this level to give what we call immune protection for the herd,” said Dr. Anthony Fauci, director of the National Institute allergies and infectious diseases. CNN’s Jim Scuitto on Tuesday.
“What that would mean would protect those who were exposed, but at the community level, there would not have been enough infections to really have enough immune protection,” said Fauci.
As a vaccine has not yet been created for the new coronavirus, some have argued that nations should give up closures altogether and try to achieve collective immunity by keeping the vulnerable inside while allowing others to live their normal lives – and be infected.
Prime Minister Boris Johnson appeared to support a similar belief in March when he suspended the ban on large rallies and the closure of schools.
However, Johnson later issued a national home stay order, effectively shutting down all non-essential businesses and banning public gatherings. He then contracted the virus himself and spent three nights in the ICU. He has since been discharged from the hospital.
Why Sweden refuses to lock
While much of Europe has locked out, one country has reversed the trend: Sweden.
Restaurants, schools and playgrounds in the Scandinavian country are open. Swedish Foreign Minister Ann Linde has said that she does not follow the theory of collective immunity, but rather relies on its citizens to make them willingly responsible for preventing the spread of the coronavirus.
But Swedish state epidemiologist Anders Tegnell said that collective immunity could be reached in the national capital, Stockholm, in a few weeks.
“In most parts of Sweden, around Stockholm, we have reached a plateau (in new cases) and we are already seeing the effects of collective immunity and in a few weeks we will see even more,” Tegnell said. said in an interview with CNBC.
The strategy did not come without costs.
The WHO said it was “imperative” that Sweden take more stringent measures to control the spread of the virus.
Compared to other European countries that have not taken more stringent measures, Sweden’s “curve” – the rate of coronavirus infections and deaths – is steeper. Sweden had at least 1,937 coronavirus-related deaths on Wednesday, up from 185 in Norway and 149 in Finland, according to data from Johns Hopkins University.
The push for antibody testing
It is difficult to say where the United States currently stands without generalized testing. This is why so many people ask for antibody tests.
With the touch of a finger, tests to find out if you have contracted the coronavirus can help public health officials determine which part of the population has been infected and, in theory anyway, has least some immunity to the virus, said Caroline Buckee, associate professor of epidemiology at Harvard TH’s Chan School of Public Health.
A city in California has already started testing antibodies to its residents. New York Governor Andrew Cuomo said his state, which is the hardest hit in the United States, will begin large-scale antibody testing within the next week.
“This will be the first real snapshot of what we are dealing with,” said Cuomo.
But scientists and doctors are skeptical about the reliability of the dozens of tests that have hit the market, as many have not been reviewed by the FDA.
Plus, even approved tests are never 100% accurate.
The FDA also warned that the tests could lead to false negatives because the antibodies might not be detectable at the start of the infection.
CNN’s Tim Lister, Sebastian Shukla, Nina dos Santos, Paula Hancocks, Yoonjung Seo, Julia Hollingsworth, Mallory Simon, Gina Yu, Curt Devine, Drew Griffin, Nelli Black, Scott Bronstein, Kristina Sgueglia, Augie Martin, Sanjay Gupta contributed this report .
